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Bifenthrin Causes Trophic Cascade and Altered Insect Emergence in Mesocosms: Implications for Small Streams
Holly A Rogers1, Travis S Schmidt1,2, Brittanie L Dabney1,3
1U.S. Geological Survey , Fort Collins Science Center, 2150 Centre Avenue, Bldg. C, Fort Collins, Colorado 80526, United States.
Environmental Science & Technology
|October 13, 2016
Summary
The insecticide bifenthrin harms stream insects and alters food webs, even at low concentrations. This common pesticide disrupts aquatic ecosystems and impacts terrestrial environments regionally.
Area of Science:
- Environmental toxicology
- Ecology
- Insecticide effects
Background:
- Direct and indirect ecological effects of bifenthrin in streams are largely unknown.
- Bifenthrin is a widely used pyrethroid insecticide.
- Aquatic insect communities are vital to stream ecosystem health.
Purpose of the Study:
- To investigate the direct and indirect ecological effects of bifenthrin on stream ecosystems.
- To compare experimental mesocosm results with a survey of natural streams.
- To assess the regional impact of bifenthrin on aquatic and terrestrial ecosystems.
Main Methods:
- Manipulative experiment using stream mesocosms with aquatic insect communities.
- Exposure of mesocosms to bifenthrin-contaminated sediment.
- Comparison of mesocosm data with a survey of 100 Midwestern streams.
Main Results:
- Bifenthrin exposure reduced macroinvertebrate abundance, richness, and biomass.
- A trophic cascade occurred: periphyton increased as macroinvertebrates decreased.
- Adult insect emergence and terrestrial subsidies were altered by bifenthrin.
Conclusions:
- Bifenthrin negatively impacts stream ecosystems at concentrations previously considered safe.
- The insecticide can cause trophic cascades and alter ecosystem functions.
- Regional extrapolation suggests widespread ecological effects of bifenthrin in streams.
